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Chapter 18: Toxic Effects of the Endophyte in Seed Straw

Abstract

Oregon produces 70% of the world supply of cool season grass seed, including tall fescue [Lolium arundinaceum (Schreb.) Darbysh.] and perennial ryegrass (L. perenne L.). About 225,000 ha of grass seed currently are in production in Oregon. Traditionally, the seed was harvested in July and August, and the straw residue in the fields was burned during August. Today, the straw is harvested and used for animal feed, principally in Japan, Korea, and Taiwan. In 2006, 33,000 containers of compressed straw were shipped to the Pacific Rim countries from U.S. Northwest ports. The production of cool season grass seed is continuing to increase, with almost all of the increase consisting of cultivars with high endophyte (Neotyphodium spp.) infestation. As a consequence, much more endophyte infected (E+) straw is being produced. Endophytes produce alkaloids that are advantageous to plants but deleterious to livestock fed straw with too high a concentration of these toxins. In this chapter, the toxic effects of straw feeding and toxin threshold levels will be discussed. Ammoniation of E+ tall fescue hay and straw can improve cattle gains but has been used to a limited extent.